JPH0350428B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electronic circuit board suitable for miniaturization or _high integration _.
The present invention relates to an electronic circuit board made of a composite body formed by filling the open pores of a porous oxide sintered body mainly composed of SiO ₂ with a resin. [Prior art] Recently, with the development of electronic industry technology, electronic component materials such as semiconductors have been becoming smaller and more highly integrated. One method for achieving this is mounting silicon integrated circuits directly on a substrate. Methods are being considered. By the way, various types of substrates for electronic circuits have been known and put into practical use, such as glass and
Epoxy composites, alumina sintered bodies, mullite sintered bodies, etc. are used. [Problems to be Solved by the Invention] However, the coefficient of thermal expansion of the glass-epoxy composite and alumina sintered body as described above is significantly different from that of silicon integrated circuits. When using a body as a substrate for electronic circuits, silicon integrated circuits that can be directly mounted are limited to relatively small ones. Furthermore, since the coefficient of thermal expansion of mullite sintered bodies can be made almost equal to that of silicon integrated circuits, it is possible to mount silicon integrated circuits directly, but mullite sintered bodies have high hardness and poor machinability. Therefore, it has been particularly difficult to manufacture electronic circuit boards with a large number of through holes. [Means for Solving the Problems] The present invention provides a substrate for electronic circuits that can solve the above-mentioned problems, that is, it has a coefficient of thermal expansion almost equal to that of silicon integrated circuits, and has excellent thermal conductivity. The purpose of this is to provide an electronic circuit board on which circuits can be directly _mounted and _has excellent _{machinability} . A composite body formed by filling the open pores of a porous oxide sintered body (hereinafter simply referred to as a porous body) with a resin, the porous body having an Al ₂ O ₃ /SiO ₂ molar ratio of 0.6. The above object can be achieved by an electronic circuit board characterized in that the viscosity is within the range of 2.0. The present invention will be explained in detail below. The electronic circuit board of the present invention needs to be a composite body formed by filling open pores of a porous body mainly composed of Al ₂ O ₃ and SiO ₂ with a resin. The reason for this is that, for example, mullite sintered bodies conventionally used as substrates for electronic circuits are dense sintered bodies, which have high hardness and extremely poor machinability. This is because the body has extremely good machinability, and since the open pores are filled with resin, it also has gas impermeability, which is essential for an electronic circuit board. The resin to be filled in the porous body includes epoxy resin, polyimide resin, trimazine resin, polyparabanic acid resin, polyamideimide resin, silicone resin, epoxy silicone resin, acrylic acid resin, methacrylic acid resin, aniphosphoric acid resin, phenol resin, Resins selected from urethane resins, furan resins and fluororesins can be used alone or in combination. The porous body of the present invention has an open porosity of 10 to 70% by volume.
It is preferable that it is within the range of . The reason for this is that if the open porosity is less than 10% by volume, the machinability will be significantly degraded, while if it is more than 70% by volume, the material will have almost no substantial strength and will be easily broken during handling. The porous body of the present invention has an Al ₂ O ₃ /SiO ₂ molar ratio of 0.6 to
Must be within the range of 2.0. The reason for this is that when the Al ₂ O ₃ /SiO ₂ molar ratio is outside the range of 0.6 to 2.0, it is difficult to bring the thermal expansion coefficient of the porous body close to that of the silicon integrated circuit. This is because it is difficult to manufacture an electronic circuit board that can be mounted and mounted on a PC. Note that the Al ₂ O ₃ /SiO ₂ molar ratio is more preferably within the range of 0.7 to 1.6. The porous body of the present invention has a crystal structure of sillimanite,
Preferably, it is at least one of andariusite, kyanite, cordierite, and mullite. The reason for this is that the thermal expansion coefficients of the sillimanite, andariusite, kyanite, cordierite, and mullite are all close to that of the silicon integrated circuit, and the silicon integrated circuit, which is the object of the present invention, cannot be directly mounted thereon. This is because it is possible to easily manufacture an electronic circuit board that can perform the following steps. The porous body of the present invention can contain CaO, MgO, etc. as components other than Al ₂ O ₃ and SiO ₂ ,
Advantageously, the amount of CaO is less than 2% by weight and the amount of MgO is less than 15% by weight. The composite of the present invention preferably has a porosity of 10% by volume or less. The reason for this is that if the porosity is greater than 10% by volume, it is difficult to provide gas impermeability, which is essential for an electronic circuit board, and a porosity of 5% by volume or less is particularly advantageous. . It is advantageous for the electronic circuit board of the present invention to have a coefficient of thermal expansion as close to that of a silicon integrated circuit as possible, preferably within the range of 2 to 6 x 10 ^- /°C, particularly 3 to 6 x 10 - /°C. Advantageously, it is within the range of 5.5×10 ⁻⁴ /°C. The electronic circuit board of the present invention has a higher thermal conductivity than a glass-epoxy composite, and has a coefficient of thermal expansion close to that of a silicon integrated circuit.
It is particularly suitable for chip-on-board type substrates that require excellent heat dissipation properties and are significantly affected by the coefficient of thermal expansion. Further, when the electronic circuit board of the present invention is required to have particularly high strength, an inorganic fiber cloth impregnated with a resin may be laminated on at least one surface of the board, or It is preferable to apply a mixture of resin and inorganic fibers to the surface of the substrate. As the resin, the same resin as the resin filled in the porous body described above can be used. It is advantageous to use glass fiber, asbestos or ceramic fiber as the inorganic fiber. Next, a method for manufacturing an electronic circuit board according to the present invention will be explained. The electronic circuit board is produced by forming a starting material mainly composed of an oxide powder having a crystal structure of at least one selected from sillimanite, andariusite, and kyanite into a green body, and then forming the green body into a green body. is made into a porous body by firing it in a non-reducing atmosphere in a temperature range where the amount of liquid phase produced is 5% by weight or less without causing crystal transformation, and then in the open pores of the porous body. It can be manufactured by filling the container with resin. The resin can be filled into the open pores of the porous body by heating the resin to melt it and impregnating it, by dissolving the resin in a solvent and impregnating it, or by impregnating the resin in a monomer state and then impregnating it. A method in which the resin is converted into a polymer or a method in which a finely divided resin is dispersed in a dispersion medium, impregnated with this dispersion, dried, and then baked at the melting temperature of the resin can be applied. Next, the present invention will be explained with reference to Examples and Comparative Examples. Example 1 2 parts by weight of polyvinyl alcohol, 1 part by weight of polyethylene glycol, 0.5 parts by weight of stearic acid and 100 parts by weight of water were added to 100 parts by weight of sillimanite powder with an average particle size of 3.7 μm and an impurity content as shown in Table 1. parts were mixed in a ball mill for 3 hours and then spray dried. An appropriate amount of this dried material was collected and molded using a metal mold at a pressure of 1.0 t/cm ² to a diameter of 40 mm and a thickness of 5 mm.
mm, and a density of 2.0 g/cm ² (60% by volume) was obtained. The formed body was placed in an alumina crucible and fired at a temperature of 1100° C. for 1 hour in air under atmospheric pressure. The crystal structure of the obtained sintered body was sillimanite, the density was 2.0 g/cm ² , and the open porosity was 37% by volume.
Moreover, the average bending strength of this sintered body was 1.5 Kg/mm ² . Next, this sintered body was impregnated with a two-component type epoxy resin under vacuum, and then cured at a temperature of about 150° C. to obtain a composite. The content of the epoxy resin filled in this composite was 16.7% by weight, and the proportion of the epoxy resin in the voids of the sintered body was approximately 100% by volume. The thermal expansion coefficient (0-300℃) of this composite is 4×
10 ^-6 /°C, specific electrical resistance of 10 ¹⁴ Ωcm or more, and relative dielectric constant of 6.2, which are extremely suitable characteristics as a substrate for electronic circuits.

【table】

[Table] Example 2 Same as Example 1, but the molding pressure was 140Kg/cm ²
A composite was obtained using the sintered body obtained by changing the method. The physical properties of the obtained sintered body and composite are shown in Table 2. As can be seen from the results shown in Table 2, lowering the molding pressure lowers the density of the sintered body,
Although the machinability of the composite was improved, there was a tendency for the coefficient of thermal expansion to become slightly higher.

〔Effect of the invention〕

As described above, the electronic circuit board of the present invention is
Because the coefficient of thermal expansion is almost the same as that of silicon integrated circuits, and the thermal conductivity is high, silicon integrated circuits can be directly mounted and mounted.Furthermore, it has excellent machinability such as drilling with a drill, etc., making it suitable for industrial use. Above all, it is extremely useful.

Claims (1)

[Scope of Claims] 1. A composite body formed by filling the open pores of a porous oxide sintered body containing Al ₂ O ₃ and SiO ₂ as main components, wherein the porous oxide sintered body is filled with a resin. The body is Al ₂ O ₃ /
An electronic circuit board characterized in that the SiO ₂ molar ratio is within the range of 0.6 to 2.0. 2 The porous oxide sintered body has an open porosity of 10 to
The electronic circuit board according to claim 1, wherein the content is within the range of 70% by volume. 3. The electronic circuit according to claim 1 or 2, wherein the porous oxide sintered body has a crystal structure of at least one selected from sillimanite, andariusite, kyanite, cordierite, and mullite. board for. 4. The electronic circuit board according to any one of claims 1 to 3, wherein the composite has a porosity of 10% by volume or less. 5 The electronic circuit board has a coefficient of thermal expansion of 2 to 6×
Claims 1 to 4 which are within the range of 10 ^-6 /℃
The electronic circuit board according to any of the above. 6. Claims 1 to 6, wherein the electronic circuit board is used as a chip-on-board type board.
The electronic circuit board according to any one of Item 5. 7. The electronic circuit board according to any one of claims 1 to 6, wherein at least one surface of the electronic circuit board is laminated with glass cloth impregnated with resin. 8. The electronic circuit board according to any one of claims 1 to 6, wherein at least one surface of the electronic circuit board is coated with a mixture of resin and glass fiber.